Formula mass is the total of all the atomic masses in a chemical formula.
To make these calculations easier, round all atomic mass numbers to the nearest whole number.
Sample Problem: calculate the formula mass of C2H5OH
Use atomic mass from the Periodic Table:
Set up your calculation this way:
element = (# of atoms) (atomic mass) = u
The units of formula mass are "atomic mass units" - u
1 atomic mass unit has an actual mass of 1.661 X 10−24 gram.
Formula Mass Calculations
Formula Mass Assignment
